Comparison of Intra Abdominal Pressure Monitoring Techniques and the Effects of the Abdominal Compartment Syndrome

Abstract

Background: Abdominal compartment syndrome (ACS) is a life-threatening condition that develops in the setting of increasing and uncontrolled intra-abdominal hypertension (IAH), leading to cardiovascular, respiratory, neurologic and/or renal dysfunction. Aims: To establish a porcine model for the evaluation of the effects of IAH on renal blood flow (RBF) and to determine if IVC pressure and/or Camino fiberoptic direct intraabdominal pressure measurements can accurately predict IAPs that have been derived using bladder pressure measurements. Methods: Abdominal laparotomy, placement of IAP and RBF measuring devices, and fascial closure were performed on six adult feeder pigs with a mean body weight of 25 +/- 5 kg. A Transonic Doppler flow probe, a suprapubic bladder catheter, a Camino fiberoptic probe, and a triple lumen central venous catheter were placed and then baseline measurements were taken of renal blood flow, bladder pressure, direct intra-peritoneal Camino pressure and IVC pressure, respectively. Normal saline was then infused into the abdomen to simulate increasing IAP. Following a 5–10-minute stabilization period, all measurements were again taken. Results: The correlation between IVC pressure and bladder pressure was 0.98, with a mean bias of -0.5 (SD 2.0; 95% CI: -0.9, -0.2). The correlation between direct IAP readings by Camino probe and bladder pressure was 0.91, with a mean bias of -3.9 (SD 4.3; 95% CI: -4.6, -3.2). There was a strong negative correlation (-0.95) between RBF and bladder pressure. At an IAP of 20 mmHg, RBF reduced by an average of 45.4% (95% CI: 40%, 50.8%). Upon abdominal decompression, RBF returned to 66.6% (95% CI: 54.3%, 78.9%) of its baseline value. Conclusions: A porcine model is effective in accurately measuring changes in real time RBF. RBF progressively declines as IAP increases, however upon decompression, it fails to achieve complete recovery. IVC pressure measurements correlate well with, and therefore may substitute, the gold standard bladder pressure measurements as representatives of IAP. Keywords: Abdominal Compartment syndrome, renal blood flow, intrabdominal hypertension, bladder pressure